There are some modifications that have the potential to void a vehicles factory warranty, but properly modifying an exhaust system after the catalytic converter is not one of them. The Magnuson-Moss Warranty Act was created in 1975 to protect consumers from invalid denial of warranty claims. Under the provisions of the Magnuson-Moss Warranty Act, an automotive dealership/carmaker cannot void your warranty simply because your vehicle has been modified with aftermarket parts. They (the manufacturers) have to prove that the failure was the direct result of the installed aftermarket part. Unfortunately, too many people have gone to a dealer to have warranty service performed on their modified vehicle only to have the dealer refuse to cover the unrelated defective items. The dealer usually states, that because of the aftermarket parts installed, the warranty is void (without ever attempting to determine whether or not the aftermarket part caused the problem). If in any case, the dealer just lifted the hood, saw the modifications, and stated that the warranty was void based on what they saw (without verifying that the failure was due to the aftermarket installation), the dealer would be in violation of the Magnuson-Moss Warranty Act of 1975. The cause of the failure must be searched out and proven in order for the carmaker to void a warranty. If you’re having problems regarding this issue, please contact the Specialty Equipment Market Association (www.sema.org) for more information regarding consumer's rights in relation to performance aftermarket parts.